Each also weighs "only" 68 pounds which probably isn't so good for unsprung mass--all the weight not supported by the car's suspension, affecting handling, steering, responses and ride quality. Protean does say that the extra unspring mass can be compensated for in other ways though, reducing the effects of significantly heavier rolling stock.

And with claimed economy improvements of up to 30 percent (depending on battery size), the benefits may offset the negatives for many. Protean also says up to 85 percent of the vehicle's kinetic energy can be recovered when braking.

Perhaps the motor's biggest benefit is that it can be retrofitted to almost anything, as demonstrated by the electic mix of demonstration vehicles.

There's no word on when the first vehicles equipped with Protean in-wheel motors will hit the road, but the benefits for larger vehicles in particular could be significant.